Back to EveryPatent.com
United States Patent | 5,121,576 |
Wu | June 16, 1992 |
An improved plastic floor tile formed with an internal stress eliminating structure including grooves or recesses disposed on the lower surface of the floor tile at four corners and four sides thereof, whereby contractile internal stress caused by thermal change can be interrupted from reaching the four corners or margin portions of the floor tile by the internal stress eliminating structure so as to effectively prevent distortion of the four corners or margin portions.
Inventors: | Wu; Yu J. (P.O. Box 1-79, Taipei, TW) |
Appl. No.: | 520559 |
Filed: | May 8, 1990 |
Current U.S. Class: | 52/309.1; 52/309.13; 52/612 |
Intern'l Class: | E04C 002/20 |
Field of Search: | 52/572,573,387,595,605,221,98,99,506,508,144,145,612,584-592,605,309.1,309.13 |
1808591 | Jun., 1931 | Bruce | 52/573. |
2269927 | Jan., 1942 | Crooks | 52/573. |
2950575 | Aug., 1960 | Hellwig | 52/221. |